Recent tree sap-collecting systems consist of a network of interconnected tubings allowing the sap collected from trees to be vacuum-sucked directly to a central sap-processing unit. In applicant's Canadian co-pending application No. 561,977 filed Mar. 21, 1988, there is described a device for collecting sap from trees that includes a member having a hollow sap-collecting section integral with a hollow sap-discharging section. The sap-collecting section has an open end which is inserted into a cavity formed in the outer layers of a tree to be sap-collected. The sap-collecting section displays thereon an annular recess in which is received expansible means to provide a sealing engagement with the tree layers and to prevent air infiltration in the first member when the sap-collecting system to which the sap-collecting device is connected is operated under vacuum conditions. A sleeve partially surrounds the sap-collecting section of the member and cooperates therewith to force the sealing means to expand to thereby secure the device in the tree cavity.
In cases where the sap-collecting system is not in operation or the device not connected to the sap-collecting tubing, a cap is required to close off the exit of the sap-discharging section.